Hong Kong Airlines has responded to the backlash surrounding its January 16 transportation of five dolphins from Japan to Vietnam. The carrier is also donating an undisclosed amount to an animal charity after an online petition urging it to stop hauling dolphins surfaced last week.

The change.org petition, which has already garnered more than 5,500 signatures, materialized after an internal email detailing the profitability of Hong Kong Airlines’ dolphin route leaked in the Chinese press. Reports also indicate that an image of the dolphins floating in shallow water accompanied the email.

Hong Kong Airlines didn’t address this allegation directly, but instead expressed its unfamiliarity with dolphin transport. “As a member of the transport industry, the airline was totally unaware of the complexities behind this shipment of five dolphins,” according to a statement posted on the carrier’s website.

“Hong Kong Airlines is very grateful for the recent input of various animal welfare organizations on the subject,” the statement continued. “Hong Kong Airlines is a responsible member for the future and the environment.”